That trio’s reasons for being absent? Federer decided to skip the entire clay-court circuit to focus on preparing for grass and hard courts. Williams is pregnant and due in the fall, with plans to return to the tour in 2018. Sharapova’s ranking wasn’t high enough to gain direct entry into the tournament as she returns from a 15-month drug suspension, and the head of the French Tennis Federation decided not to give her a wild card.

Still, there are plenty of story lines to keep an eye on at Roland Garros, where play begins Sunday.

Here is what to watch on the red clay courts of the year’s second Grand Slam tournament:

ANDRE AND NOLE

Novak Djokovic has been in a slump for nearly a year (his last Grand Slam title came at the 2016 French Open, when he won his fourth major in a row) so he opted to shake things up. His latest move was bringing aboard Andre Agassi as a coach for the French Open; they were out there practicing in Paris on Thursday. Agassi won eight major titles – four fewer than Djokovic – but has never coached. “It felt like we know each other for a very long time. We clicked and connected very fast,” Djokovic said. “He’s someone that inspires me a lot.”

NADAL’S RESURGENCE

Winning three clay-court tournaments in a row signaled that Rafael Nadal is back and again a candidate to win the tournament he has dominated the way no man has dominated any Grand Slam event. Could he win his 10th French Open championship a year after withdrawing before the third round with an injured left wrist?

LIFE IS HARD AT NO. 1

Both players ranked No. 1 right now in singles, Andy Murray and Angelique Kerber, have been struggling most of the year. Murray is 16-7 with one title; Kerber is 19-10 with no titles and a 0-7 record against top-20 players. “Last year, I just played, and there was pressure,” Kerber said, “but this year is more like, ‘OK, the expectations are bigger.'”

WHICH WOMAN WILL STEP UP?

Williams or Sharapova would have been popular picks to win the French Open. Without them, there is no clear favorite to take the title. Simona Halep, the runner-up in 2014 and maybe the best current player without a major trophy, has been playing well on clay, but she tore a ligament in her right ankle recently. Other women who could make a splash include No. 3-ranked Karolina Pliskova, a finalist at the U.S. Open in September, or No. 6 Elina Svitolina, who just won the Italian Open on clay.

GENERATION NEXT

This is the first week in the 40-years-plus history of the ATP computer rankings that the top five men are all 30 or older. When that quintet of major champions (Federer, Nadal, Djokovic, Murray and Stan Wawrinka) finally slows down, there will be a gap at the top. Worth keeping an eye on some of the up-and-coming younger guys in Paris, such as Alexander Zverev, Dominic Thiem and Nick Kyrgios.

KVITOVA’S RETURN

Two-time Wimbledon champion Petra Kvitova will make her return to action Sunday at Roland Garros, less than six months after being stabbed during an attack at home in the Czech Republic. Kvitova’s first match will be the first match of this year’s tournament in Court Philippe Chatrier, the French Open’s main stadium, against Julia Boserup of the United States.

AMERICAN TEEN

Amanda Anisimova, a 15-year-old from New Jersey, became the first player born in 2001 to earn a spot in a Grand Slam main draw when she claimed the U.S. Tennis Association’s wild card for the French Open. She’ll also be the youngest player in the French Open since Alize Cornet in 2005. Anisimova, who reached the junior final in Paris last year, plays in the first round Sunday against Kurumi Nara, a 25-year-old from Japan who is ranked 90th.

SWINGIN’ IN THE RAIN

The French Open is still the only Grand Slam tournament without a roof – there are plans to have a retractable cover above the main stadium in a few years – and things did not go well last year. An entire day of play was washed out, the first time that happened at the event in 16 years, and other weather-related decisions by tournament officials drew criticism from players.

Men to watch at the French Open, where play begins Sunday:

ANDY MURRAY

Ranked: 1

Age: 30

Country: Britain

2017 Match Record: 16-7

2017 Singles Titles: 1

Career Singles Titles: 45

Major Titles: 3 – Wimbledon (’13, ’16), U.S. Open (’12)

Last 5 French Opens: ’16-Runner-Up, ’15-Lost in Semifinals, ’14-SF, ’13-Did Not Play, ’12-QF

Aces: Reached at least semifinals on four of past five appearances – losing to Rafael Nadal or Novak Djokovic each time. … Ranks only 39th on tour by winning 78 percent of his service games in 2017.

Topspin: Neither his serve nor movement are up to par this season. If he can’t get those straightened out, his stay in Paris could be short.

NOVAK DJOKOVIC

Ranked: 2

Age: 30

Country: Serbia

2017 Match Record: 20-6

2017 Singles Titles: 1

Career Singles Titles: 67

Major Titles: 12 – French Open (’16), Australian Open (’08, ’11, ’12, ’13, ’15, ’16), Wimbledon (’11, ’14, ’15), U.S. Open (’11, ’15)

Aces: Last year’s title in Paris made him first man since Rod Laver in 1969 with four consecutive major championships. … Also made him eighth man with career Grand Slam. … Hasn’t won a major trophy since.

Topspin: Not that long ago, was far and away the favorite at every tournament he entered. That aura has disappeared. … Will be intriguing to see what effect his trial coaching partnership with Andre Agassi has.

STAN WAWRINKA

Ranked: 3

Age: 32

Country: Switzerland

2017 Match Record: 20-8

2017 Singles Titles: 1

Career Singles Titles: 16

Major Titles: 3 – French Open (’15), Australian Open (’14), U.S. Open (’16)

Last 5 French Opens: ’16-SF, ’15-W, ’14-1st, 13-QF, ’12-4th

Aces: Lost 4 of 6 clay-court matches entering tuneup at Geneva but won title there Saturday. … 2015 French Open trophy makes him only 30-or-older men’s champion in Paris since Andres Gomez in 1990.

Topspin: No matter how poorly he might be playing entering a Grand Slam tournament, the sport’s biggest stages tend to bring out his best lately. If that beautiful one-handed backhand is clicking, watch out.

Aces: Only man with nine trophies from one major. … Withdrew from last year’s French Open before third round because of injured left wrist but seems back at his healthy best lately.

Topspin: Popular pick to win 10th championship, and rightly so, given his history of dominance on red clay and recent resurgence on the surface, including a 17-match winning streak and three consecutive tournament titles.

DOMINIC THIEM

Ranked: 7

Age: 23

Country: Austria

2017 Match Record: 29-12

2017 Singles Titles: 1

Career Singles Titles: 8

Major Titles: 0 – Best: SF, French Open (’16)

Last 5 French Opens: ’16-SF, ’15-2nd, ’14-2nd, ’13-DNP, ’12-DNP

Aces: Grand Slam breakthrough a year ago marked him as an up-and-coming contender. … Playing well on clay in 2017, beating Andy Murray and Rafael Nadal; losses came against Nadal, Novak Djokovic and top-20 player David Goffin.

Topspin: Knack for strong returning – he ranks eighth on clay-court matches in 2017, breaking 31 percent of the time – and solid all-around game make him a threat to beat anyone on any given day.

ALEXANDER ZVEREV

Ranked: 10

Age: 20

Country: Germany

2017 Match Record: 27-9

2017 Singles Titles: 3

Career Singles Titles: 4

Major Titles: 0 – Best: 3rd, French Open (’16), Australian Open (’17), Wimbledon (’16)

Last 5 French Opens: ’16-3rd, ’15-DNP, ’14-DNP, ’13-DNP, ’12-DNP

Aces: Victory over Novak Djokovic in Italian Open final made Zverev youngest to win a Masters 1000 event since Djokovic a decade ago. … Also allowed Zverev to make top-10 debut.

Topspin: Still inexperienced, but the 6-foot-6 (1.98-meter) Zverev possesses the skills and temperament to take a big step into the second week of a major tournament.

JACK SOCK

Ranked: 15

Age: 24

Country: United States

2017 Match Record: 22-8

2017 Singles Titles: 2

Career Singles Titles: 3

Major Titles: 0 – Best: 4th, French Open (’15), U.S. Open (’16)

Last 5 French Opens: ’16-3rd, ’15-4th, ’14-3rd, ’13-2nd, ’12-DNP

Aces: Half of his losses this season came against top-10 players (Rafael Nadal, Roger Federer, Milos Raonic).

Topspin: Game doesn’t necessarily appear built for clay – big serve, big forehand – but some of his best results have come on the slow surface, which he says he enjoys competing on.